Rumination is the chronic regurgitation of previously ingested food and is a behavior pattern that can sometimes lead to death. The mortality rate attributed to chronic rumination in institutionalized mentally retarded individuals ranges from 12 to 20 percent. The rumination literature largely focuses on practical procedures for managing the behavior. While it suggests that these methods can be effective when appropriately administered, they are not reliably successful and must often be used on a chronic basis. Furthermore, their applicability is constrained by legal, regulatory, and logistical restrictions. A new direction for rumination research was established when it was reported that the quantity of food ingested at the meal was inversely related to the amount of post-meal ruminating. Further research parametrically clarified this relation and isolated some of the properties of the food that effect this relation. This application proposes a project whose long-term objectives are to identify the variables responsible for the development and maintenance of ruminating and to construct with those variables practical procedures for treating rumination. The identification of the variables controlling ruminative behavior will be pursued through a series of four experiments examining the consistency of the diet that influences oropharyngeal and esophageal stimulation, the caloric density of the diet, the role of liquids, and the inter-meal interval. The application of these and existing findings to the formulation of a treatment program will begin by collating a set of parameters of client characteristics that guide the individualized selection of a sequence of program components. Then each subject will be exposed to a formal sequence of component procedures designed to clarify component interactions and to provide long-term treatment for the subject. The research program will have a substantial physiological component designed to assess the role of structural, functional, and metabolic factors through a series of medical tests both before and after the behavioral studies. This research will also provide valuable data concerning dietary regulation and eating disorders, orpharyngeal stimulation, and the treatment of other self-stimulatory response classes ranging from PICA to obesity.